EO Sterilization for Medical Devices

A panel at www.bio2devicegroup.org discussed Ethylene Oxide (EO) Sterilization of Bio/Medical Devices on Tuesday, March 1, 2022. The panel consisted of Denny Christensen, CEO of Sterilization Validation and Consulting, Michael Anderson, Site Director at Infinity Laboratories, and Sam Sohal, President of Test-O-Pac Industries and EO Sterilization.

EO sterilization was discovered in 1928 and used as an insecticide in hospital rooms. In the 1940s, EO began to be used to sterilize spices and food preservatives. However, in 1948 it was found that EO could potentially cause cancer and that rang some alarm bells. But it was eventually found that the risk was miniscule in the amount used.

Currently EO sterilization is used in 50 percent of medical devices. In fact, EO has become a dominant method for sterilization of all disposable medical devices. FDA has been investigating alternative gas methods for sterilization but we are not closer to finding anything that can replace EO in the short term.  

EO is a valuable compound and is very versatile. Over 17 million tonnes of EO is produced annually, worldwide. EO is used in antifreeze, heavy machinery, acrylics, plastics, glue, paper, fabrics, carpets, polyester, cosmetics and more. EO also plays a massive role in sterilization of medical devices. There are two primary factors that drive its usage for medical devices. First, EO is consistently compatible with the majority of other materials and second, it can be performed at low heat. Other vaporized gas materials are often not compatible with cellulose, paper etc. For many medical devices, sterilization with Ethylene oxide may be the only method to effectively sterilize a device without causing damage. Medical devices made from certain polymers (plastic or resin), metals or glass or those that have multiple layers of packaging or hard to reach places like catheters are likely to be sterilized with ethylene oxide. Additionally, other gas alternatives are challenging to scale up because they can’t be effectively packaged in cardboard and shipped to various locations, with ease.

EO is regulated and controlled by FDA and EPA and shutdowns sometimes lead to shortages. There is a need for public information and there is need to balance use of EO with public and environmental safety. EO is an effective sterilization method and we will continue to need EO sterilization since there are fewer other efficient alternatives. 

It is also important to understand how EO can be used more effectively in medical devices. Four active ingredients required to deliver a successful process are: heat, humidity or moisture, gas concentration and time. Achieving a high sterility level reduces the chance of microbes and resulting infections. Additionally, EO sterilization companies need to have open communication with the designers of medical devices. Earlier medical device companies start thinking about sterilization, the more they can take full advantage of optimum sterilization process that in the end saves time, resources and helps the public and environment by achieving optimum sterilization with less exposure.

In summary, it was mentioned that state of the art technology will continue to evolve and enable fine tuning of sterilization cycles. Additionally, better planning and early communication between device engineers and sterilizers and consideration of the sterilization process in the design phase will mean fewer sterilization challenges later. Also important is communicating to those handling the devices that thorough cleaning of these devices prior to sterilization is of immense importance in helping minimize risk of infection through unclean devices. 

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